Discharge opening and closure for concrete mixers



Sept. 1, 1931. DURHAM 1,821,056

DISCHARGE OPENING AND CLOSURE FOR CONCRETE MIXERS Filed July 22 1929 INVENTOR kennegh F? Durham ATTORNEY Patented Sept. 1, 1931 UNITED STATES PATENT orrica KENNETH 1. DURHAM, OF SEATTLE, WASHINGTON, ASSIGNOR TO MOB-BIS & BOOGHER,

. INC., .A CORPORATION OF WASHINGTON DISCHARGE OPENING AND CLOSURE FOR CONCRETE 'MIXEBS ,y Application filed July 28, 1929. Serial No. 880,002.

My invention refers to the art of transit concrete mixers and more particularly to a discharge opening and closure therefor.

In transit concrete mixers of the type employing mixing paddles and particularly in that type where the addles are pitched sofas to move the materiaFtowa-rds the rear of the mixer, I have found that the continual movement of material by the successive paddles tends to cause a severe packing of the material at the rear end of the machine- It is to overcome this fault that I have created my dump door. I have further found also that it is not desirable to have a mixing blade close enough to one end of the mixer so that a rock may wedge in between the mixing blade and the end of the mixer. My device also overcomes this objectionable feature; therefore:

The principal object of my invention is to provide a dump door which is so positioned and so constructed as to prevent any packing of materials adjacent to the door.

A further object is to provide such a shape to the rear end of the mixer that any material being propelled rearwardly will meet a gradually rising surface near the end of the mixer and will be forced upwardly, thus preventing any packing.

A still further object is to so position my discharge opening that the mixing and propelling blades need not be positioned close to the end of the mixer.

A further object is to provide means whereby the door covering said discharge opening may beheld tightly against the face of the mixing drum, yet on opening, may be easily released from this tight engagement.

The above general objects of my invention. together with others inherent in the same will be obtained by the device illustrated in the following drawings, the same being a preferred form of embodiment of my invention, throughout which drawings like reference numerals indicate like parts.

Figure 1 is an elevation of a transit concrete mixer shown as customarily mounted upon a motor truck and showing my construction and device in elevation.

Figure 2 is a rear-elevation of the mixer the same purpose.

shown in Figure 1, being intended to show the method of holding my door in place.

Figure 3 is a fragmentary transverse section showing my discharge door and the end of the mixer associated therewith in greater detail.

Figure 4 is a fragmentary elevation of the locking mechanism employed to seat my door firmly against the mixer body.

Figure 5 is a cross section throiigh the same locking mechanism as shown in Figure 4. 1

Referring to the drawings, represents the main body of a transit concrete mixer mounted on a motor truck T and having the associated parts such asvthe water tank 12, the trigears 14, the power takeoff chain 15, and a central mixing shaft 17. This partof. the disclosure is all old and is not claimed in this application. The point of novelty and which I claim' as my invention resides in the rear end construction in which I have a portion of a spherical surface in which I provide a discharge opening 22 and a cover or door 24 for said discharge opening. Door 24 is pivotally' supported from point by arms 31 and 32. This I-believe it will be apparent, is only my preferred construction as a single heavy arm could be made to serve I have found in operating my door ,thatit is essential that the door 24 be pressed very tightly against the curved surface 20 inasmuch as the cement used in this production of concrete is exceedingly fine and unless a very tight joint is secured, a leak is sure to result. If this cement is allowed to leak out on a highway, for instance, it will quickly harden and form a very tight bond with the road surface and as a result most cities have ordinances prohibiting the use of any equipment capable of doing this. It is to overcome this fault that I have provided the locking mechanism shown in Figures 4 and 5 in which the supporting arms 31 and 32 unite at their upper end to form a circular boss 40. Inside ofthis circular boss I have provided an cecentric 42 which is supported in turn by the eccentrically positioned pin 44. A control centric 42 and serves as an operating means.

A lug'48 is secured to the arm 32 in such a 7 position that it will be engaged b the bail 46.

- I believe it will be clear that should not be bound to this exact locking mechanism as several will immediately suggest themselves to anyone familiar with this type of con-V struction. However, the one shown has proven the most satisfactory.

I have shown the pivot 30 as belng at the vcenter of the mixer, thereby making surface 20 a portion of a spherical surface. This will be found, I believe, the most satisfactory construction, although I have constructed the ends of similar machines wherein point 30 would be moved substantially half way to the door 24. In this construction of course the surface is no longer spherical but becomes a curved surface to which it is much more diificult to tightly fit a door. Further, the direction changing feature which is illustrated in Figure 3 by the arrows 51 becomes more abrupt due to this decrease in radius and except where unusual conditions are met, I do not care to use that construction.

Method of operation In operating my device it is necessary only to grasp the bail 46 and pull it rearwardly. The first action is to revolve the eccentric 42 Other details of the operation in my invention will be so obvious tothose skilled in the art that I' believe no further description will be necessary. .Manifestly, however, changes may be-made in the form, proportions and arrangements of parts of my invention without departing from the spirit thereof.

What I claim is:

1. In a transit concrete mixer, a curved rearsection, a discharge opening in said curved section, a similarly curved cover for said opening, a supplort forsaid cover and means adapted to tlg tly seat the cover when in closed position.

2. In a transit concrete mixer, a rear section formed as part of a spherical surface, a discharge opening in said spherical surface, a similarly curved cover for said opening and means for supporting said cover.

3. In a transit concrete mixer, a rear section formed as .part of a spherical surface, a discharge openin in said spherical surface, a similarly curve cover for said opening, a support for said cover and means adapted to tightly seat the cover when in closed position.

In witness whereof, I hereunto subscribe my name.

KENNETH P. DURHAM.

thus forcing the door 24 away from the surface 20. As the rearward movement is continued, bail 46 meets with the lug 48 and a continued movement will move the .door 24 rearwardly and upwardly to a position substantially as indicated by the dashed lines 53 in Figure 3. The material that has been moved to the rear of the machine either by elevating the forward end or mechanically by the pitched propelling blades, is dis-.

charged through the opening 22. Further,

any material adjacent the rear end of the A mixer will not be able to repose on the steep J curved surface and will slough or slide downwardly and out the discharge opening 22. As soon as the discharge of material has been complete the handle 46 is released and the door byits own weight or aided by hand if necessary, will assume its closed position. It is then necessary to shove the bail 46 forward, thus turning the eccentric 42 in the reverse direction, which will carry with it the arms 31 and 32 and the door 24 and raise it up until it comes to a securely tight position.

It is desired to call attention to the fact that this particular door arrangement makes it possible to discharge the material from this type of mixer much higher than is usual. It. will naturally follow then that the entire mixer may be set lower on the truck and still maintain the same dumping heighth as would be possible with achute. 

